Automatic fuel cutoff



Oct.r14, 1941. A. J. SCOTT. JR

AUTOMATIG'FUEL CUTOFF Filed June 6, 1939 Arc/uhdd JJGOZZ'J/J ATTORNEYSPatented Oct. 14, 1941 O F E AUTOMATIC FUEL CUTOFF. v Archibald J.Scott, Jr.', West Warwick,'R. 1., as-

signor of one-half to Fred Greenwich, It. ll.

Application llunc 6, 1939, Se!

4 Claims.

The present invention relates to an automatic fuel cut-01f for internalcombustion engines and the like. a v 7 An important object of thepresent invention resides in the provision of a device adapted to beinterposed between the oil pressure line and fuel pump of an internalcombustion engine or-the like whereby a reduction of pressure in-the oilline will cause the device to operate to cut off the supply of fuel tothe engine thereby arresting motion of the same.

Another object of the invention resides in the provision of a devicehaving the above characteristics actuated by the pressure of thelubricating system whereby if the oil pressure becomes; dangerously low,air will be drawn. into the fuel pump in the place of fueltherebystopping motion of the engine to prevent injury to the movingparts of the same due to improper lubrication.

The invention will be fully and comprehensively understood from aconsideration of the following detailed description when read inconnection with the accompanying drawing which forms a part of theapplication.

In the drawing:

Figure .1 is a vertical sectional view of the device being shownattached to a fuel pump. j

Figure 2 is a fragmentary detail view of the device attached to amodified form of fuel pump, and

Figure 3 is a transverse sectional view taken substantially on line 3-3of Figure ,1.

Referring to the drawing for a more detailed description thereof, thereis. disclosed a fragmentary sectional view of a conventional fuel pump 5to which the cut-off device generally designated by the numeral 6 isattached. As is well known, the portion 1 of the fuel pump is generallyprovided with a plug or cap having a stem portion extending within thesamefor supporting a coil spring 8 for normally retaining the inletvalve 9 to the pump in closed position. Fuel from the tank is drawn intothe pump through the line Ill where it passes through the strainer Hbefore being fed to the remainder of the pump structure, not shown,through the inlet l2. The action of the pumped fuel raises the valve 9against the tension of the spring 8 permitting its passage to the pump.This action of the fuel pump is conventional and forms no part of thepresent invention, the description being given in order to set forth themanner in which air will be fed to the carburetor by the fuel pumpinstead of fuel from the supply tank.

The device 6 is attached to the portion 1 of the D. Briggs, 1 EastiaiNo. 277,740 1 2 fuel pump being substituted for the conventional plugas shown in Figure 1 of the drawing. The device, Gcomprises asubstantially cylindricalshapedhousing l3 the interior of which issubstantially hollow. The lower end of the housing l3 is'reduced andthreaded as indicated atl4 for attachment withthe interiorly threadedportion 1 of the fuel pumpi5. The end i4 is further reduced and projectswithin the fuel pump as in dicated at l5 for supporting thereonthe'tension spring 8. r V

The upper end of the housing I3 is exteriorly threaded for receiving aninteriorly threaded cap it, a washer or the like I! effecting anair-tight seal. A conduit l8 extending from the oil pressure line isattached to the cap 16 and has communication with the interior of thehousing I3 for a purpose to be hereinafter described.

The interior of the housing l3, adjacent the bottom end thereof, isformed with a projecting collar portion IS, the same tapering upwardlyand forming -a shoulder 20 for supporting a coil spring 2!. A piston 22supported on a rod 23 is vertically movable within the chamber 3| formedby the collar IS, the upper end of the rod 23 having a reduced end 24 towhich isattached a pair of leather or the like plunger cups 25, saidplunger cups being secured to the rod by means of the metal washer 26and nut 21. r The plunger cups 25 form a seal for the interior of thehousing l3 to prevent the entrance of oil from the pressure line l8.- Itwill also be noted that the coil spring 2| is disposed between theshoulder portion 2!! and the cups 25, said spring tending to normallyurge the rod 23, piston 22 and cups 25 upwardly against the pressure ofthe oil from the conduit l8. Should any oil escape beyond the cups 25within the housing it will be returned to the crankcase through theoutlet pipe 28 threadedly secured to the housing l3 adjacent theshoulder portion 20.

The lower end of the piston 22 has attached thereto a leather washer 29,the same being countersunk for receiving the nut 30 which retains thepiston and Washer on the rod 23, it being understood that a shoulder isformed on the lower end of the rod by reducing the diameter thereofagainst which the piston abuts.

The chamber 3| in which the piston 22' operates, has connection with thefuel pump 5 through the line 32, the chamber 3| being open to theatmosphere through the inlet 33 formed in the lower end of the housing[3. When the pressure of the oil line is normal the piston 22 will coverthe inlet 33 thereby preventing the admission of air to the fuel pumpthus allowing the pump to operate normally. However, should the pressurein the oil line drop below normal, the spring 2| will raise the rod 23and piston 22 thereby uncovering the inlet 33 allowing the fuel pump todraw in air through the chamber 3| and line 32 which will be fed to thecarburetor. The air being fed through the fuel pump will retain thevalve 9 against its seat thereby preventing the admission of fuel intothe carburetor thus stopping the engine and alleviating the possibilityof. injury to the parts thereof.

In Figure 2 of the drawing, the device is shown attached to a fuel pump34 such as used with V- type motors in which case it is necessary toemploy a T-fitting 35 interposed between the fuel line 36 and pump 34.It will be noted that the reduced end of the housing I3 is threadedlyattached at 31 to the fitting 35. The operation of the device when usedwith this type of fuel pump is precisely the same as previouslydescribed.

Also it will be understood, of course, by those skilled in the art thatvariations in the hereinabove described device involving thesubstitution of substantial equivalents for the devices described areintended to be comprehended within the spirit of. the present inventionand that the invention is capable of extended application and is notconfined to the exact showing of the drawing nor to the preciseconstruction described and, therefore, such changes and modificationsmay be made therein as do not affect the spirit of the invention norexceed the scope thereof as expressed in the appended claims.

What is claimed is:

1. An automatic fuel cut-off of the character described for internalcombustion engines having a fuel supply including a fuel pump and alubricating system having a pipe line through which the lubricant iscirculated under pressure, comprising, a housing adapted to' be attachedto the fuel pump, means for connecting said housing to one end of thepipe lineof the lubricating system, one nd of said housing being formedwith an inwardly projecting annular member defining a chamber, avertical shaft movable within said chamber and supporting on one endthereof a piston, the other end of said shaft supporting sealingcup-like members having engagement with the walls of said housing, meanswithin said housing surrounding said annular member for urging saidcup-like members and shaft against the pressure of the lubricatingsystem, said housing having a conduit formed in one wall thereofcommunicating with said chamber for admitting atmospheric air therein,said piston normally maintaining said conduit closed, and means forproviding communication between said chamber and the fuel pump to admitair to said fuel pump upon an abnormal decrease of pressure in thelubricating system at the time the said means within the housing willraise said piston to uncover the air admitting conduit of said chamber.

2. An automatic fuel cut-off for internal combustion engines,comprising, in combination, a fuel pump and a lubricating system inwhich the lubricant is circulated under pressure, a housing having oneend attached to said fuel pump and its other end connected in the lineof the lubricating system, a cylinder formed in one end of said housing,said housing being formed with a vent for admitting atmospheric air tosaid cylinder, said cylinder having communication with said fuel pump,and means operable in said cylinder governed by the pressure of thelubricating system for covering and uncovering said vent to control theadmission of air through said cylinder into said fuel pump.

3. An automatic fuel cut-off of th character described for internalcombustion engines having a fuel supply including a fuel pump and alubricating system in which the lubricant is circulated under pressure,comprising, a housing having one end attached to the fuel pump and itsother end connected to the lubricant pressure line, a cylinder formedwithin said housing, a rod movable within said housing and supportingonone end thereof a piston operable within said cylinder, said cylinderhaving communication with said fuel pump, said housing being formed witha vent for admitting atmospheric air into said cylinder, and meanswithin said housing adapted to operate said piston to uncover said ventfor admitting air to said fuel pump upon abnormal decrease of pressurein said lubricating system.

4. An automatic fuel cut-off of the character described for internalcombustion engines having a fuel supply including a fuel pump and alubricating system having a pipe line through which the lubricant iscirculated under pressure, comprising, a housing having one end attachedto the fuel pump, means for connecting the other end of said housing tothe pipe line of the lubricating system, the lower end of said housingbeing formed with an inwardly projecting annular member defining achamber, a shaft movable within said chamber and supporting on one endthereof a piston, the other end of said shaft extending above saidchamber and carrying 'cuplik members having engagement with the walls ofthe housing, the pressure within the lubricating system normally urgingsaid piston and cup-like members within said chamber and housing, meanswithin said housing for urging said cup-like members and shaft towardthe outer end of said housing against the pressure of the lubricatingsystem, said housing being formed with a vent for admitting atmosphericair to said chamber and said chamber being connected with said fuelpump.

ARCHIBALD J. SCOTT, JR.

